Matt Carlsson, previously dedicated to teaching clients about energy efficiency and the decarbonization of buildings, faced a significant frustration: many clients simply lacked the economic incentive to act on his recommendations. Realizing that a solid business case was essential for driving change, he shifted his focus to bitcoin, an unexpected move for someone passionate about climate change.
Bitcoin mining is known for its energy-intensive process, which results in substantial heat generation. This heat is a byproduct of the computational effort required to verify transactions on the blockchain. In 2024, bitcoin mining accounted for about 0.5 percent of global electricity use, emitting significant heat as well. This led Carlsson to wonder if this excess heat could be harnessed for beneficial purposes.
Currently, he is involved in a groundbreaking project with MARA Holdings, a bitcoin mining company that is utilizing waste heat from local cryptocurrency miners to provide heating for 80,000 residents in Finland. The operation involves cooling their computers with water, which then emerges at high temperatures, ranging from 122 to 172 degrees Fahrenheit (50 to 78 degrees Celsius). This heated water flows through the existing district heating systems, substantially reducing the necessity for traditional boilers.
The environmental impact has been notable, with MARA reporting a reduction in greenhouse gas emissions equivalent to the output of 700 U.S. homes since launching its project. Carlsson envisions expanding this model globally, a sentiment shared by others in the industry. Joint bitcoin mining and heating initiatives are gaining traction in Finland, where the climate and infrastructure are particularly conducive to such projects.
For example, Terahash Energy’s “Genesis” project also repurposes waste heat to serve industrial and residential needs. Hashlabs, another firm, operates multiple sites across Finland linking bitcoin miners with district heating systems, reflecting a growing trend in sustainable energy solutions. Alen Makhmetov, co-founder of Hashlabs, emphasizes the dual revenue streams generated by such operations, which mitigate the risk associated with fluctuating bitcoin prices.
MARA’s chief strategy officer, Adam Swick, assertively characterized this approach as a “no-brainer” due to the potential for generating income from both bitcoin mining and heating services. Districts pay for heat while benefiting from the cooling of miners, all at a lower cost than conventional electric heating options.
Residents may remain largely unaware of the operational changes, as the heating is sourced from the same pipes they’ve always used, creating a seamless transition. The company also assumes all costs associated with the equipment and offers the heating at a competitive price.
From an environmental standpoint, MARA’s operations contribute to a reduction in reliance on biomass and peat, which have traditionally powered district heating systems in Finland. As a result, the company claims to have mitigated nearly 5,000 tons of greenhouse emissions since their districts began operation.
Nevertheless, not all district heating systems are suitable for this strategy. Higher efficiency systems, particularly those drawing heat from co-generation plants, present obstacles for integrating bitcoin mining as a heat source. Experts point out that while bitcoin mining does offer a method to reuse waste heat, it isn’t the most efficient approach available.
Replacing traditional heating methods with electric heat pumps could provide superior efficiency, but costly infrastructure investments make this transition formidable for many buildings. For regions reliant on imported fossil fuels, bitcoin mining can help address heating needs at a lower cost, especially in response to rising energy prices due to geopolitical tensions.
Critics, including representatives from Greenpeace, caution against endorsing bitcoin mining as a solution without scrutinizing its broader implications for climate policy. They argue that while it may help in the short term, it doesn’t justify the overall energy consumption associated with bitcoin mining, which uses more electricity than some small countries.
Carlsson, now a firm proponent of the synergy between bitcoin and waste heat recovery, reflects on his journey from skepticism to advocacy, even likening himself to a “missionary” for the cause. However, experts warn that expanding operations like MARA’s might inadvertently lead to increased emissions due to greater reliance on fossil fuel power plants to meet the energy needs of bitcoin mining.
Despite its potential benefits, the consensus remains that while utilizing waste heat from bitcoin mining may be a practical solution for certain circumstances, it should not become a dependency in the long-term strategy for addressing climate change.
